My wife has been on 2.5L of liquid O2 for 3 years so we have learned a lot since we go south for 6 months during the winter. After trying several methods and vendors we went with Lincare as they have a good nation wide network of providers who have the liquid O2. We have two medium size liquid tanks that we rotate so she has a steady supply of O2 readily available. She uses a concentrator that runs on 115 VAC during the day and the liquid at night, plus she has the small Helios liquid tank that I can fill off the medium liquid tank and that will last her about 7 hours on 2.5L when we want to go out. I can get the liquid tanks filled in Montana, Idaho, Nevada, Arizona and New Mexico, which is about the extend of our travels, without a problem. In some cases they will come right to the CG and fill the empty tank and help me put it in the coach. I can lift the full tanks from my pickup and take it inside the coach but it's about all I want to lift, but through the generosity of fellow RV'ers I rarely have to do this alone. We have tried the compressed O2 and other means to travel with but the liquid and Helios tanks have worked very well for us for years. We just call our home office and they fax the travel vouchers to the next location we will need a refill and it's worked perfectly for us. If you need more info PM me.
Bob Retired Army Traveling alone now.
2008 Camelot 40 PDQ 4 slides ISL400 towing a 2016 Dodge Ram 1500 4x4 Quadcab
Western MT in summer, AZ, NV in winter